Religious education teacher Gordon McFarlane moves confidently about the small classroom at Bridge of Don Academy, talking to his attentive students, occasionally addressing one by name or gently chiding another for not paying attention.

Outwardly, he is giving a normal lesson at the smaller of the two secondaries on a huge Aberdeen housing estate. The only sign of anything unusual is the presence of Yulie, a large friendly golden Labrador with a distinctive fluorescent harness, lying quietly in a basket under his desk.

Mr McFarlane is totally blind, but it is taken for granted that he is just as capable of teaching at the school as he has been for 24 years. He has the backing of an understanding local authority, a supportive staff and the students.

“In some ways,” he says, “disability in the classroom is about communication - and it hasn’t stopped that. It was difficult for a while, but there is technology to assist me and the pupils’ response to me hasn’t changed. In that sense communication has continued.

“I think it opens up an avenue that maybe 20 or 30 years ago would not have been there. There were blind teachers before, but now, with the law behind it, provision has to be made for disabled people, assuming they are able to do the job.”

Headteacher Bob McClymont says: “For ourselves in the school, for the pupils, for Gordon, and for the city council as well, to accommodate and cope with the situation, it’s been remarkable.”

For a few years Mr McFarlane refused to admit to himself or society at large that he was seriously visually-impaired. What is more, he successfully concealed from his students that his sight was failing, although the school authorities were aware of his disability.

“I was coping reasonably well,” he says. “I had so many adaptations that people didn’t really know I was seeing very little.”

The situation came to a head three years ago when he was crossing a field behind the school on a daily journey he had made from his home nearby for more than 20 years.

“I was in the middle of the field when I realised I couldn’t see the edges. I was lost. It was a silly thing really. Then some of the kids saw me and they had to bring me to school. I realised then that I was going to have to do something.

“It cost me a lot of anguish to admit that I was totally blind.”

Mr McClymont also recognised it was a critical point in the teacher’s career and life. “It was a major decision for Gordon to regard himself as a blind person. Previously, he had regarded himself as sight-impaired, but it was a big step to say, ‘Well, I am blind’.”

Mr McFarlane’s problems were first recognised at the age of 16 when he was diagnosed with glaucoma in both eyes. After a series of operations, he was warned that eventually his sight could go completely.

“People wouldn’t have really known I was visually impaired. I was registered but I was just on the borderline,” he says.

“Because I had missed so much education, however, I went to the Royal Blind School, which is where I got the necessary qualifications for Edinburgh University.”

With a degree in divinity, he intended to become a minister. “Then it seemed that teaching was an interesting area. I felt it was good to be able to communicate with children and I found that I was able to manage that.”

He became an RE teacher at Bridge of Don Academy and now, as head of religious studies, is one of its longest-serving members of staff.

“It was about 10 years ago that I realised my vision was slowly going. Fortunately, I had taken up computer programming. So when I needed to make adaptations in order to continue to teach, I could set up programs which didn’t require much vision,” he says.

He admits that he was in denial about his sight. “I was coping and I had made so many adaptations people really didn’t realise. One of the things about teaching is that it is so easy to cover up.”

By then Mr McFarlane had two grown-up sons. All the members of his family are visually-impaired. “I found I was leading a double life: one at home, the other at school.

“It got to the point where I was seeing very little. What a relief it was the day I told the kids that I was totally blind. I had burnt my boats. I couldn’t go back.”

The admission to his students came some time after what he calls his “embarrassing moment” in the field. “It was three years ago this past June and there was a change in the school timetable. I had to make a decision about what to do the following year.”

He had applied for a guide dog, but avoided going for training. “I didn’t want to be seen as blind.

“I was in quite a bit of torment. I remember one night trying to reason it out. I realised I would have to face things. Finally, I came to the decision that I would have to tell everybody.”

He told his headteacher first. “When I arrived six years ago he was undergoing a fairly rapid deterioration,” says Mr McClymont. “Then he came to the critical point and we had long discussions about what should be done. It was a major decision for him to regard himself as blind. It was a very important step for him to take, not only as a teacher but as a man.”

Mr McFarlane was then persuaded to go on a guide dog training course and soon Yulie came to join the staff at the academy.

He then told the pupils in class and in assembly. It was remarkable how many of them never knew about his disability, he says.

“They have been great about it, very supportive and none of them has tried to take advantage,” says Mr McClymont.

The school and local authority never considered any other course of action than to allow Mr McFarlane to continue teaching. He had been appointed as a handicapped person - a supernumerary who was not paid from the school budget - and like others with disabilities, Grampian categorised him as “policy-protected excess”.

Mr McClymont consulted Liberty Occupational Health, the authority’s disability advisers. With the aid of the clerk of works, and Mr McFarlane himself, they put in place the alterations that would make life in the classroom easier for him and his students.

Contrary to initial impressions, his classroom is not ordinary. His desk is a long bench accommodating his computer array, there is an overhead projector and large screen to help with textual lessons and another feature is a closed circuit television camera linked to a monitor in an adjoining room.

“I was a bit concerned about infringement of rights,” Mr McFarlane acknowledges, “but a letter was sent to parents inviting them to see the system operating. The point we made was that it was for security - not for me, but the pupils. There were no complaints.”

He laughs. “In the first year, the camera was used about three or four times to pick out whoever was out of their seats. That sorted them out. The next year it was used twice but this year I have never used it for a disciplinary matter. One of the kids said he had forgotten it was there.

“Mind you, I often surprise them by what I can hear.”

Using his computer skills he has adapted programs to enable scanned documents to be read back to him. In addition, a reader is employed for 12 hours a week so that he can mark written material.

The easy rapport between Mr McFarlane and his pupils is palpable. Meanwhile, on standby, Yulie sleeps in her basket, satisfied her master is managing perfectly well without her guidance.